Born in Flavia Neapolis, Palestine around AD 100, near the close of the New Testament period, Justin was the son of pagan Greek parents. He was a philosophy student who studied in Alexandria, moving from Stoicism to Pythagoreanism and then Platonism as he sought to make sense of life. for converted to the Christian faith and became a teacher in Ephesus and Rome. He writes that his conversion came as he observed the steadfast faith of Ephesian martyrs and through an elderly Christian whom he met along the shore of the sea.

Justin probably wrote much more than we have preserved, but three extant works show his intellect, his never completely abandoned Platonic philosophical education, and his inclination toward apologetics — that is, an intellectual defense of the Faith.

In his First Apology, addressed to Emperor Antoninus Pius and his adopted sons, Justin defended Christianity as the only rational creed. He included accounts of contemporary baptismal and communion rites, quite possibly designed to rebut distorted accounts from anti-Christian sources. Some of these anti-Christian writings claimed that Christians were cannibals (probably because of a distorted second hand understanding of the Lord's Supper).

He addressed his Second Apology to the Roman Senate. It counters spurious charges of immorality and the like that were being made against Christians. He said that only those who misunderstood the Faith would accuse it of undermining Roman society and countered that Christians made good citizens.

His Dialogue with Trypho the Jewish rabbi shows him at his strength. He carefully defended Christian teaching while allowing that the Church would continue to welcome Jews and would let them remain faithful to the laws of the Torah. While he may have edited it to provide himself with a few good lines, the text reads as a faithful exposition of an actual conversation.

Justin was living in Rome when the cynic philosopher Crescens stirred up trouble for the Christians. After refusing to make pagan sacrifices, Justin was arrested, tried and executed, along with six other believers, including Charites, Paeon, and Liberianus. The official Roman court proceedings of his trial before Rusticius, a Roman prelate, document his confession of faith. The account of his martyrdom became a source of great encouragement to the early Christian community.

Much of what we know of early liturgical practice comes from Justin. For example, in the First Apology he gave this brief description of Holy Communion: "On finishing the prayers we greet each other with a kiss. Then bread and a cup of water mixed with wine are brought to the leader and he, taking them, sends up praise and glory to the Father of the Universe through the name of the Son and of the Holy Spirit, and offers thanksgiving at some length that we have been deemed worthy to receive these things. When the leader has finished the prayers and thanksgivings, the whole congregation assents, saying, 'Amen.' ('Amen' is Hebrew for 'So be it.') Then those whom we call deacons give to each of those present a portion of the consecrated bread and wine and water, and they take it to the absent."

Almighty and everlasting God, who found Your martyr Justin wandering from teacher to teacher, seeking the true God, and revealed to him the sublime wisdom of Your eternal Word, grant that all who seek You, or a deeper knowledge of You, may find and be found by You; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, now and forever.